Meteorological variables, phenology, plant health and crop management, soil physical and chemical properties, water and energy balances as well as variables related to economics, logistics and monitoring processes, among others, create complexity in the management of irrigation, which make it difficult to be administered conceptual or empirical models. Also, physico-mathematical modelsdescribing isolated phenomena cannot cover the overall complexity of the problem. This can be seen, in practice, by the gradual growth of factors which threaten the sustainability of irrigation enterprise. Currently, the advent of geotechnology application in agriculture and its integration with weather information in Geographic Information System (GIS) environments has make possible a more detailed support for irrigation management and planning. The objective of this study therefore was to organize and develop a geo-relational database with information from 30 pivots located in Cruz Alta, RS, Brazil, to further establish the usefulness of GIS in irrigation management. Data base preparation took place in two stages: (i) acquisition, georeferencing, image vectorization, snipping and calculation of vegetation indices relating to 107 images from Landsat5/TM satellite; and (2) creation of geo-related tables for each pivot containing information obtained from fieldsand weather stations in the region. Besides statistical analysis of NDVI values of pixels (picture elements) from each pivot, informationon crop type, planting date, phenological stages, soil type, evapotranspiration and weather data were also included in the database. Image processing, calculations and statistical analyzes, as well as mapping were done using SPRING software. Thus, a geographical database capable of integrating field information with those obtained by remote sensing was created and mapping of the distribution of key crop variables enabled better visualization of the dynamics of processes in progress, thus enabling comprehensive technical background for decision making with respect to planning and management of production systems in irrigated agriculture.
O uso de geotecnologias como ferramenta de inclusão digital vêm crescendo paulatinamente nos trabalhos acadêmicos. O presente trabalho tem por objetivo proporcionar um contato inicial com vistas à inclusão digital de pescadores artesanais, por meio de geotecnologias. Para o ensino ser mais produtivo são necessários métodos atrativos que despertem o interesse dos alunos. Portanto as atividades digitais desenvolvidas foram direcionadas para os conhecimentos e assuntos de interesse dos pescadores. Utilizando uma imagem do satélite Landsat 5, o aplicativo Google Earth e Google Maps, os vinte e um pescadores consultados conseguiram identificar, em três aulas, sete alvos conhecidos, são eles: 1. local de pesca; 2. rios; 3. ilhas; 4. bombas de arroz; 5. porto da cidade; 6. área urbana; e 7. ponte. As classes, “local de pesca”, “rios” e “ilhas” foram identificados por 100% dos pescadores que participaram das aulas. A atividade proporcionou aos pescadores uma visualização de pontos para a comercialização do pescado, como a área urbana e a foz do rio Ibicuí, pois identificaram seus locais de pesca próximos a estas regiões. O grupo também se mostrou motivado para aprender a se localizar e identificar locais de atividades alternativas, como possíveis pontos turísticos da região, para assim diversificar sua atividade.
Monthly spatial distribution of physicochemical variables in a urban watershed (Itaqui, RS, Brazil)Abstract: This study identifies spatial and temporal changes in the concentration of physicochemical water variables of urban watersheds at the city of Itaqui (RS, Brazil). The concentrations of dissolved oxygen, potassium, pH, sodium, chloride and electrical conductivity were measured from September to November 2010 and 2011. Results were statistically processed through Pearson correlation and spatially interpolated using the "nearest neighbor" algorithm implemented in Spring, the free brazilian GIS software. Three tendencies were identified with reference to the legal limits: 1) low concentrations in the southeastern area; 2) high concentrations downstream of the urban area; 3) high concentrations upstream of the urban area when the Uruguay river level was low (136 cm). Palavras-chave:Spring; SIG; interpolador vizinho mais próximo; qualidade da água.
RESUMOEste trabalho tem por objetivo analisar as relações entre variáveis de uso, cobertura do solo e limnológicas em uma área de 170 km 2 no município de Itaqui. Para isso, utilizaram-se imagens satelitais e dados limnológicos coletados in situ durante os meses de setembro a novembro de 2011. A área de estudo foi dividida em 12 microbacias nas quais foram identificadas seis classes de uso e cobertura do solo: lavoura de arroz; campo nativo; vegetação arbustiva; mata ciliar; área urbanizada e área industrial. A inferência estatística baseou-se no uso do coeficiente de correlação de Spearman entre as variáveis limnológicas e a porcentagem das áreas de uso da terra. Os resultados analisados referem-se aos dados que obtiveram um grau igual ou maior a 95% de confiança segundo o teste de correlação. As conclusões sugerem que os efeitos da contaminação dos corpos hídricos da região de estudo podem ser provenientes da área urbana e do campo nativo, pois apresentaram correlações significativas com as variáveis de mesófilos, 0,71 e 0,65 respectivamente. Esse fato aponta para os efluentes da cidade e para a contaminação originária da pecuária extensiva como principais fontes de contaminação das águas. Palavras-chave:Uso e Cobertura do Solo; Sistema de Informação Geográfica; Contaminação da Água. ABSTRACTThe objective of this study was to analyze the relationships between land use and limnological variables in an area of 170 km 2 in the municipality of Itaqui. For this, we used data from satellite images and limnological analysis collected in situ during the months of September to November, 2011. The studied area was divided into 12 watersheds in which were identified five classes of land use: rice crop, native grassland, shrub, and riparian forest industry. Statistical inference was based on the use of the Spearman correlation coefficient between limnological variables and the percentage of the areas of land use. The laboratory analysis and sampling procedures followed the recommendations of the Standard Methods. The results analyzed refer to the data that obtained a confidence interval equal or greater than 95% according to the correlation test. However it appears that the effects of contamination of water bodies of the region under study are related to urban areas and native pasture, because they showed significant correlations with the variables of mesophilic bacteria (0.71) and (0.65) respectively. This fact points to the city's wastewater and the extensive cattle ranching as sources of water contamination.
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